Greg is in a car at the top of a roller-coaster ride. The distance, d, of the car from the ground as the car descends is determi
ned by the equation d = 144 – 16t^2, where t is the number of seconds it takes the car to travel down to each point on the ride. For which interval of time is Greg’s car moving in the air?
We can figure out how many times a heart beats in one minute (so we can figure out how many minutes it will take for 140 times) by dividing 700 by 10. This gives us 70. Now we know that a heart beats 70 times each minute. Now we know it would take 2 minutes for a heart to beat 140 times because 70×2=140.